The present invention relates to apparatus for detecting success in weft insertion on shuttleless looms, more particularly relates to improvement in the apparatus for detecting success in weft insertion in photoelectric manner on looms on which wefts are inserted into sheds being carried on air or water jet flow ejected from a nozzle located on one side of the loom width.
In the case of the known non-contact type photoelectric system for shuttleless looms of the above-described kind, a light source and a photoelectric cell are arranged being spaced from each other on the trimmed selvage side of the loom width and their operating terminals, i.e. the light emitting and the light receptive terminals, confront to each other while defining a detecting zone between them. The arrangement is so designed that, upon successful arrival of the inserted weft at the trimmed selvage side of the loom width, the leading end of the weft passes across the detecting zone and the photoelectric system detects the success in the weft insertion.
In order to carry out the above-described photoelectric detection successfully always, it must be assured that the leading end of the inserted weft always passes across the detecting zone without fail. When the leading end of the weft flys outside of the prescribed detecting zone, the photoelectric system cannot sense the presence of the weft end, the weft insertion is judged as being ended in failure and the corresponding signal from the photoelectric system stops the loom running. In actual weaving, it often happens that the leading end of the interested weft dances or whips upon arrival at the trimmed selvage side and such dancing and whipping tend to cause the weft end to fly just outside of the photoelectric detecting zone and, thereby, unnecessary stoppage of the loom running results.
The unnecessary stoppage of the loom running of this kind causes fatal lowering in the production efficiency especially when the photoelectric detecting system is employed in combination with the unattended continuous mass running system in weaving mills, which currently shows a rapid penetration into the textile industry all over the world.
In addition to the above-described drawbacks in the conventional photoelectric system, it should be noted that, even when the weft end once passes across the detecting zone successfully, its dancing and/or whipping may cause faulty double detection by the detecting mechanism.
The primary object of the present invention is to provide apparatus for reliably detecting success in weft insertion on shuttleless looms without any ill influence by the dancing and/or whipping of the weft end upon arrival at the trimmed selvage side.
A further trouble may arise when the photoelectric detection system is used on so-called water jet looms. As already described, weft is inserted into sheds being entrained on water jet flow and, therefore, the leading end of the weft is usually wetted. When the wet weft end passes across the detecting zone, water drops accompanying the weft end tend to fly to the surfaces of the operating terminals of the light source and the photoelectric cell. Presence of such water drops on the operating terminal surfaces and covering of the surfaces with water layers tend to lower the detecting ability of the photoelectric system, i.e. they tend to produce undesirable noises in the detection.
The other object of the present invention is to provide apparatus particularly suited for detecting success in weft insertion on water jet looms being free of noises produced by wetting of the photoelectric system.